A DEEP VERY LARGE ARRAY RADIO CONTINUUM SURVEY OF THE CORE AND OUTSKIRTS OF THE COMA CLUSTER

2009 ◽  
Vol 137 (5) ◽  
pp. 4436-4449 ◽  
Author(s):  
Neal A. Miller ◽  
Ann E. Hornschemeier ◽  
Bahram Mobasher
Keyword(s):  
Radio Continuum ◽  
Large Array ◽  
Coma Cluster ◽  
Very Large Array ◽  
The Core

scholarly journals A Multi-Epoch Study of Radio Continuum Emission from Massive Protostars

2020 ◽  
Author(s):  
W O Obonyo ◽  
S L Lumsden ◽  
M G Hoare ◽  
S E Kurtz ◽  
S J D Purser
Keyword(s):  
Spectral Index ◽  
The Other ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Gas Bubble ◽  
Large Array ◽  
Proper Motions ◽  
Very Large Array ◽  
The Core ◽  
Displacement Vectors

Abstract We report the results of the Jansky Very Large Array (JVLA) observation of five massive protostars at 6 and 22.2 GHz. The aim of the study was to compare their current fluxes and positions with previous observations to search for evidence of variability. Most of the observed sources present the morphologies of a thermal core, hosting the protostar and exhibiting no proper motion, and associated non-thermal radio lobes that are characterised by proper motions and located away from the thermal core. Some of the protostars drive jets whose lobes have dissimilar displacement vectors, implying precession of the jets or the presence of multiple jet drivers. The jets of the protostars were found to have proper motions that lie in the range 170≤v ≤650 kms−1, and precessions of periods 40≤p ≤50 years and angles 2≤α ≤ 10○, assuming that their velocities v =500 kms−1. The core of one of the sources, S255 NIRS 3, which was in outburst at the time of our observations, showed a significant change in flux compared to the other sources. Its spectral index decreased during the outburst, consistent with the model of an expanding gas bubble. Modelling the emission of the outburst as that of a new non-thermal lobe that is emerging from a thermal core whose emission enshrouds that of the lobe also has the potential to account for the increase in flux and a decrease in the spectral index of the source’s outburst.

Bipolar outflow of gas in the spiral galaxy NGC 3079

1986 ◽  
Vol 64 (4) ◽  
pp. 531-535 ◽  
Author(s):  
Nebojsa Duric ◽  
E. R. Seaquist
Keyword(s):  
Spectral Index ◽  
Spiral Galaxy ◽  
Central Region ◽  
Qualitative Description ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Bipolar Outflow ◽  
The Galaxy

Very large array, radio-continuum observations of the edge-on spiral galaxy NGC 3079 are presented. The observations reveal that the nucleus has windlike properties and that the central region of the galaxy exhibits an unusual figure-eight morphology that shows evidence of severe depolarization and a flattening spectral index away from the nucleus. A qualitative description of a model is presented to account for the observed radio properties. It is shown that a wind-driven shock propagating away from the nucleus and focused by the ambient disk gas can give rise to the observed morphology.

scholarly journals Low frequency (74 MHz) radio continuum observations of the inner 13° × 7° of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 464-466
Author(s):  
M. Rickert ◽  
F. Yusef-Zadeh ◽  
C. Brogan
Keyword(s):  
High Resolution ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Galactic Center ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Image Displays ◽  
Western Side

AbstractWe analyze a high resolution (114″ × 60″) 74 MHz image of the Galactic center taken with the Very Large Array (VLA). We have identified several absorption and emission features in this region, and we discuss preliminary results of two Galactic center sources: the Sgr D complex (G1.1–0.1) and the Galactic center lobe (GCL).The 74 MHz image displays the thermal and nonthermal components of Sgr D and we argue the Sgr D supernova remnant (SNR) is consistent with an interaction with a nearby molecular cloud and the location of the Sgr D Hii region on the near side of the Galactic center. The image also suggests that the emission from the eastern side of the GCL contains a mixture of both thermal and nonthermal sources, whereas the western side is primarily thermal.

scholarly journals Quasi-simultaneous Radio/X-Ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6−1125 during its Low-luminosity Accretion-disk State

2021 ◽  
Vol 923 (1) ◽  
pp. 3
Author(s):  
Amruta D. Jaodand ◽  
Adam T. Deller ◽  
Nina Gusinskaia ◽  
Jason W. T. Hessels ◽  
James C. A. Miller-Jones ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Millisecond Pulsar ◽  
Very Large Array ◽  
X Ray ◽  
Upper Limit ◽  
5 Ghz ◽  
Variable Radio

Abstract 3FGL J1544.6−1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs—PSR J1023+0038, IGR J18245−2452, and XSS J12270−4859—3FGL J1544.6−1125 shows γ-ray emission and discrete X-ray “low” and “high” modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission—possibly originating from a compact, self-absorbed jet, the “propellering” of accretion material, and/or pulsar moding. 3FGL J1544.6−1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6−1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 μJy down to ≲15 μJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L 5 GHz = (2.17 ± 0.17) × 1027 erg s−1 for a quasi-simultaneous X-ray luminosity L 2–10 keV = (4.32 ± 0.23) × 1033 erg s−1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6−1125 is a tMSP showing similar phenomenology to PSR J1023+0038.

scholarly journals Observations of H2O maser and continuum emission in AFGL 2591

2002 ◽  
Vol 206 ◽  
pp. 68-71
Author(s):  
Miguel A. Trinidad ◽  
Salvador Curiel ◽  
Jorge Cantó ◽  
José M. Torrelles ◽  
Luis F. Rodríguez ◽  
...  
Keyword(s):  
Radio Continuum ◽  
Continuum Emission ◽  
Molecular Flow ◽  
Large Array ◽  
Very Large Array ◽  
Star Forming ◽  
Bipolar Outflow ◽  
Maser Line ◽  
H Ii Region

We report results of radio continuum (1.3 and 3.6 cm) and H2O maser line observations, made with the Very Large Array (A configuration), toward the star-forming region AFGL 2591. We detected 85 maser spots toward this region, which are distributed in three main groups. Two of these groups spatially coincide with the radio continuum sources VLA 2 and VLA 3. The maser spots associated with VLA 3 are distributed along a shell-like structure of 0.01 and nearly perpendicular to the CO bipolar outflow. We propose that VLA 3 is the center of the observed molecular flow in this region. Finally, we confirm that AFGL 2591 region is a cluster of B type stars, each one with its own optically thin H II region.

scholarly journals A multifrequency study of the active star forming region NGC 6357

2006 ◽  
Vol 2 (S237) ◽  
pp. 400-400
Author(s):  
C. E. Cappa ◽  
R. H. Barbá ◽  
M. Arnal ◽  
N. Duronea ◽  
E. Fernández Lajús ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Massive Stars ◽  
Radio Continuum ◽  
Large Array ◽  
Schmidt Telescope ◽  
Ionized Gas ◽  
Very Large Array ◽  
Active Star ◽  
Star Forming ◽  
Spiral Arm

To investigate the interaction of the massive stars with the gas and dust in the active star forming region NGC 6357, located in the Sagittarius spiral arm at a distance of 1.7-2.6 kpc (Massey et al. 2001), we analyzed the distribution of the neutral and ionized gas, and that of the dust, based on Hα, [OIII] and [SII] images obtained with the Curtis-Schmidt telescope at CTIO, radio continuum observations at 1.465 MHz obtained with the Very Large Array (NRAO) in the DnC configuration (synthesized beam = 38″), Hi data from the Parkes survey (angular resolution = 15′), CO(1-0) observations obtained with the Nanten radiotelescope at Las Campanas Observatory (angular resolution = 2.7′), and IR images in the four MSX bands (angular resolution = 18.3″).

scholarly journals A VLA Radio Continuum Survey of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 60-60
Author(s):  
A. Zijlstra ◽  
S. R. Pottasch ◽  
C. Bignell
Keyword(s):  
High Resolution ◽  
Planetary Nebulae ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array

With the Very Large Array it is now possible to make high resolution radio continuum maps with sensitivity less than a milliJansky in an observation of only 5 minutes. We have used this so-called snapshot capability to measure about 400 PN north of declination −35. Most of the measurements were carried out at 6 cm. Some of the stronger sources were observed at several frequencies. Most sources were detected, however many nebulae were too weak to map in detail. The resolution ranges from 1.5″ to 1′, depending on the size of the PN. The selected PN have sizes in the range from 4″ to 6′.

scholarly journals A Sub-arcsecond Study of Ionized Gas in NGC 253

2001 ◽  
Vol 205 ◽  
pp. 400-403
Author(s):  
K.R. Anantharamaiah ◽  
Niruj R. Mohan ◽  
W.M. Goss
Keyword(s):  
Mass Function ◽  
Star Cluster ◽  
Initial Mass Function ◽  
Radio Continuum ◽  
Starburst Galaxy ◽  
Large Array ◽  
Nuclear Region ◽  
Ionized Gas ◽  
Very Large Array ◽  
Stellar Density

The nuclear region of the starburst galaxy NGC 253 was observed in H92α (8.3 GHz) and H75α (15.4 GHz) recombination lines at sub-arcsecond resolution using the A-configuration of the Very Large Array (VLA). In the highest resolution observations at 15.3 GHz, we have detected a compact (< 5 pc), high density (> 5 × 104 cm−3) ionized region which is nearly coincident with the radio continuum peak near the nucleus. Modeling of RRL emission from this region shows that about 1000 O stars are needed to maintain the ionization. Assuming the Salpeter initial mass function, the implied overall stellar density corresponds to that of a super star cluster.

Looking for new water-fountain stars

2018 ◽  
Vol 14 (S343) ◽  
pp. 527-528
Author(s):  
L. Uscanga ◽  
J. F. Gómez ◽  
B. H. K. Yung ◽  
H. Imai ◽  
J. R. Rizzo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Magnetic Fields ◽  
Mass Loss ◽  
High Velocity ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Evolved Stars

AbstractWe carried out simultaneous observations of H2O and OH masers, and radio continuum at 1.3 cm with the Karl G. Jansky Very Large Array (VLA) towards 4 water-fountain candidates. Water fountains (WFs) are evolved stars, in the AGB and post-AGB phase, with collimated jets traced by high-velocity H2O masers. Up to now, only 15 sources have been confirmed as WFs through interferometric observations. We are interested in the discovery and study of new WFs. A higher number of these sources is important to understand their properties as a group, because they may represent one of the first manifestations of collimated mass-loss in evolved stars. These observations will provide information about the role of magnetic fields in the launching of jets in WFs. Our aim is to ascertain the WF nature of these candidates, and investigate the spatial distribution of the H2O and OH masers.

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